Reason #5: Some commentaries explain that it is on account of the Geirim that Yisrael are in Galus ...

Source: ... as the Gemara says in Pesachim (Daf 87b) 'Why are Yisrael scattered throughout the lands more than other nations? So that Geirim will join their ranks'.

Refutation: But this is not correct, since the Gemara says in Yevamos (Daf 47a) 'When a Nochri comes to convert, we say to him "What made you decide to convert?" ... You should know that Yisrael are rejected and knocked down?'

Refutation (cont.): ... and the Gemara explains there that this is to encourage him to retract - since Mar said that Geirim are hard on Yisrael a plague of Tzara'as ...

Refutation (concl.): So we see that it is after they convert that they are 'hard'.

Reason #6: Rav Avraham the Ger explains that it is because Geirim are conversant with the Mitzvos and are meticulous in their practice , that they are hard on Yisrael like a plague (See Hagahos ha'Bach) ...

Reason #6 (cont.): Because, on account of them Hakadosh-Baruch-Hu remembers the sins of Yisrael when they do not do His will.

Precedent: ... much in the same as we find by the Tzorfis (in Melachim 1, 17) who said to Eliyahu "What do you have against me, man of G-d, that you came to me to mention my sins?" - Because since he was a perfect Tzadik, it seemed to her that he was reminding Hash-m of her sins.

Reason #7: Whereas according to the Ri, they are hard because they married into Yisrael, and 'the Shechinah only rests on a family that is Meyuchas (of pure pedigree).

Proof: And so it seems, because that will explain why the Gemara cites Rebbi Chelbo's statement on that of Rebbi Chama bar Chanina.

Clarification: ... who is Meyuchas from four mothers (See Daf 76a) ...

Clarification (cont.): ... because as far as marrying a Yisre'elis is concerned, no Chezkas Kashrus is required, since that is permitted in any case ...

Source: ... as the Gemara says elsewhere - (in Yevamos, Daf 45a) in connection with 'A Nochri who is born from a Nochri who had relations with a bas Yisrael', to whom we say 'Go to a place where you are not known or marry a woman like yourself!' ...

Source (cont.): ... from which we see that in a place where he is unknown, he may accept the Yisre'elis that he is given.

Explanation #1: According to the context, Rashi explains, it appears that Bavel is situated between these two large rivers - the Chidekel and the P'ras, one on the east, the other, on the west. They both flow from south to north, until eventually the P'ras flows into the Chidekel. All of this , says Rashi, we can learn from here.

Explanation #1 (cont.): Eretz Yisrael is situated south of Bavel, as the Pasuk writes "The evil will begin from the north" (Yirmiyah 1) - so we see that Bavel in in the north ...

Explanation #1 (cont.): .. and the P'ras flows down from Eretz Yisrael to Bavel - as the Gemara states in Shabbos (Daf 65b) 'Rain in Eretz Yisrael serves as a testimonial for the P'ras' - since its water then increases and fills its banks ...

Explanation #1 (concl.): ... and the Gemara asks (We know that what lies between the two rivers is Bavel, and the question is) regarding the land that lies outside the Chidekel (and the P'ras?) - up to where does the width of Bavel extend? Rav says 'Up to the River Azak ... '.

Explanation #2: Rabeinu Tam however, explains that the River P'ras flows from north to south, since it comes from the east of Eden (Bereishis 2), and Gan Eden is in the north of the world (See Masores ha'Shas), Eretz Yisrael in the south - and the P'ras flows from Eden from north to south.

Implied Question: ... and when the Gemara says 'Rain in Eretz Yisrael serves as a testimonial for the P'ras', implying that it flows from south to north ...

Answer: What it means is that the water of P'ras increases to such an extent that it flows back in the reverse direction - from south to north